Annealing furnace



- March 5, 1929. F T COPE 1,704,036

ANNEALING FURNACE Filed NOV. 20, 1924 Patented Mar. 5, 1929.

UNITED STATES PATENT oEFlcE.

FRANK T. COPE, 0F SALEM, OHIO, ASSIGNOR T0 THE ELECTRIC FUBNACE COMPANY, OF SALEM, OHIO, A; CORPORATION OF OHIO.

ANNEALING FURNACE.

Application led November 20, 1924. Serial No. 751,025.

This invention relates to the annealing and heat treating of wire and the like, and pertains more particularly to an improved non-oxidizing method of annealing or heat treating wire in an electric furnace.

The objects of the invention are to prevent oxidation of the wire under treatment and to prevent arcs by contact of the wire with the furnace, thus eliminating pits inV the wire.

The above and other objects may be attained by passing the'wire to be treated through an electrical contacting device which may be a molten bath of lead or the like, thence through an elongated tube and afterwards through a second contacting device, the two molten baths of lead and the tube through which the wire is passed, being all located in an electric circuit, which not only assists in producing the necessary heat to keep the lead ,in molten state and to heat the tube to properly anneal the wire, but also prevents oxidation and pitting of the wire b contact with the tube since there is no di erence in potential between the wire and the tube.

Oxidation may be'further eliminated by extending each end of the tube into the adjacent molten bath of lead, thus sealing the tube and preventing the wire from .contacting with the outer atmosphere during the time it is passing through the tube.

' An embodiment of the invention is illustrated in the accompanying drawing, in Which- Figure 1 is a longitudinal, sectional view through a furnace illustrating the improved method of annealing; and

Fi 2, a cross section of a modified form of tu e.

Similar numerals refer to similar parts throughout the drawing.

The furnace to which the invention pertains, may comprise an elongated shell 1 closed at its ends as by the heads 2 of insulation material, a metal tube 3 extending centrally through the furnace and protruding from each end thereof, the space between vthe tube and shell being lled with suitable heat insulating material, such as kiesel- 'gphr or thelike, as indicated at 4.

- An electrode 5 may be provided upon each end` portion of the tube 3 in the form of a.

depending projection, to which thewires 6,

leading from the transformer 7 or other source of electric energy, are connected. A tank'8 containing a bath of lead or the like, as shown at 9,may be connected to the electrode 5 at the inlet end of the furnace, and a similar tank 8a containing a bath of lead or the like, as indicated at 9a, may be connected to the electrode at the discharge end of the furnace, and in order to hermetically vseal the tube 3 to prevent oxidation, the ends of the tube may be bent downward, as shown at l() and extended into the lead baths, effectually sealing the tube, although when it is not desirable or necessary to prevent oxidation, the tube may terminate at points spaced from the contacting devices.

It will be evident that the electric current thus passes not only throughA the tube 3, but also through the fluid conductor baths of lead. For the purpose of preheating the baths in t-he tanks when lead or other metals freezing at temperatures above normal are used, vin starting the furnace, any suitable form of auxiliary heater, such as shown at 11, may be provided, and the auxiliary heater at the entrance end of the furnace will be maintained throughout the operation, due to the chilling effect of the cold wire entering the bath.

A roller 12 is provided in the lower portion of each of the tanks, and in annealing the wire, indicated at 13, the same is progressively drawn from a reel 14 located near the tank 8, being passed downward through the molten bath of lead beneath the roller 12 and then through the tube 3 and into the bath of lead in the tank 8, under the roller 12 and wound upon a rcel 15.

It will be seen that the electric circuit passes entirely through the length of' sealed wire from one molten bath to the other, as

Well as entirely through the tulie, thereby maintaining equal electrical potential in and about or surrounding the wire, eliminating any arcs which might injure the Wire by contact of the Wire with the tube at any point, while oxidation of the wire is prevented by sealing the opposite ends of the tubes in the molten baths.

When the wire being treated is bright, a contacting device comprising a pairof ltension rollers or other tension device may be substituted for the fluid conductors which,

however, give better results when the wire is oxidized or corroded by reason of the larger contact surface afforded.

Due to the diiiiculty of constructing heat resisting alloy tubes of considerable length, it may be desirable to sometimes form the external heater for the wire of a sheetA formed into U-shape as shown at 3 in Fig. 2, t0 substantially surround the wire, brick or the like, as shown at 3b, being provided for closing the open side thereof.

1. A furnace for annealing or heat treating wire or the like, including a hermetically sealed tube, means for passing a Wire. through the tube, and means includingjluid,

conductors for passing an electric current through the wire and tube.

2. A furnace for annealing or heat treating wire or the like, including a tube, a fluid conductor at each end of the tube, means for passing a wire through the fluid conductors and tube, and means for passing an electric current through the` fluid conductors and tube. y

8. A furnace for annealing or heat treating wire or the like, including a tube, a'

tank in contact with each end of the tube, molten lead in said tanks, means for passing a Wire through the tanks and tube, and

means for passing an electric current FRANK T. COPE. 

